I haven't seen any that don't require calibration, even after a month or so mine was off by 0.2.
The one I picked up was the Hanna pHep4 from "thesilvergenie" on Ebay at http://stores.ebay.com/Sunstone-Herbals. I do regret not paying the extra few dollars for the pHep5 because it has accuracy to .01 instead of .1. It works great though. If I was to purchase again I would probably get the Hanna pH/TDS/temp one.